As Mars’s atmosphere thinned and its surface became cold, dry and irradiated billions of years ago, any surviving microbial life may have found its last refuge underground. Yet the environments most c
A recent scientific review suggests that if microbial life ever existed on Mars, it likely retreated underground to escape the planet's harsh, irradiated surface. Researchers are now evaluating how different depths and geological environments might have served as potential refuges for ancient life.
Why it matters
This shifts the focus of astrobiology research, suggesting that future Mars missions may need to prioritize deep-subsurface exploration to find evidence of past or present life.
We may be looking for Martian life in all the wrong places—and at depths we cannot yet reach.
Mars has a life-search problem built into its geology. The material we can reach most easily sits in the part of the planet least suited to preserving, let alone sustaining, an organism.
The modern surface is cold, dry and chemically oxidising. Mars’s atmosphere is about one per cent as dense as Earth’s, liquid water is generally unstable in the open, and the planet has no global magnetic field to deflect charged particles from the Sun. Ultraviolet light and energetic particles reach the ground with far less shielding than they receive on Earth.
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